Publications by authors named "Raphael Gross"

30 Publications

  • Page 1 of 1

Gait Alteration Due to Haemophilic Arthropathies in Patients with Moderate Haemophilia.

Int J Environ Res Public Health 2022 06 20;19(12). Epub 2022 Jun 20.

Inserm, UMR 1229, RMeS, Regenerative Medicine and Skeleton, Nantes Université, ONIRIS, 44042 Nantes, France.

Some patients with moderate haemophilia (PWMH) report joint damage potentially responsible for gait disorders. Three-dimensional gait analysis (3DGA) is a relevant tool for the identification of complex musculoskeletal impairment. We performed an evaluation with 3DGA of 24 PWMH aged 44.3 ± 16.1 according to their joint status [Haemophilia Joint Health Score (HJHS) < 10 or HJHS ≥ 10] and assessed the correlation with the radiological and clinical parameters. Sixteen had HJHS < 10 (group 1) and eight had HJHS ≥ 10 (group 2). They were compared to 30 healthy subjects of a normative dataset. Both knee and ankle gait variable scores were increased in group 2 compared to the controls ( = 0.02 and = 0.04, respectively). The PWMH of group 2 had a significant increase in their stance phase, double support duration, and stride width compared to the controls and group 1 ( < 0.01). Very low correlations were found for the ankle gait variable score with the ankle Pettersson sub-score (r = 0.250; = 0.004) and ankle HJHS sub-score (r = 0.150; = 0.04). For the knee, very low correlation was also found between the knee gait variable score and its HJHS sub-score (r = 0.290; < 0.0001). Patients with moderate haemophilia presented a gait alteration in the case of poor lower limb joint status.
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http://dx.doi.org/10.3390/ijerph19127527DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9223556PMC
June 2022

Social Media in Health Studies: A Systematic Review of Comparative Learning Methods.

Int J Environ Res Public Health 2022 Feb 15;19(4). Epub 2022 Feb 15.

CHU Nantes, Service de Médecine Physique et Réadapatation Locomotrice et Respi-Ratoire, 44093 Nantes, France.

Learning modifications particularly increased due to the SARS-CoV-2 pandemic, which made it necessary to offer distance health education for many months. Social media allows students to have interactive activities such as discussing specific subjects or sharing data with each other, and also to have interactions with their teachers and tutors. So, we aimed to compare the effects of the use of social media on knowledge, skills and perceptions in health students compared to other methods. We performed a systematic review on PubMed, ScienceDirect and Embase about comparative learning methods using social media. The search followed PRISMA guidelines, and the quality assessment of the studies was performed using the Medical Education Research Quality instrument (MERSQI). Eight studies were analyzed including 1014 participants. Mean age ranged from 19.9 to 23.4 years, and 70% were females. About 54.4% of the participants were medical students and 20.9% were dental students. The mean MERSQI was 11.7 ± 2.6. Various subjects were included-anatomy, cultural competences, sterile surgical techniques, radiology, arthrocentesis, medical pathologies and cariology. As far as knowledge evaluation was concerned, we found that the use of social media may have had a positive effect from a short-term point of view but results concerning skills were less consistent across studies. Students usually had a positive perception of the use of social media as a complementary method but not as a complete alternative so it is not excluded that this effect might result from an increase in working time. The impact on patient care should also be assessed in future studies.
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http://dx.doi.org/10.3390/ijerph19042205DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8871930PMC
February 2022

A practical guide to optimizing the benefits of post-stroke spasticity interventions with botulinum toxin A: An international group consensus.

J Rehabil Med 2021 Jan 1;53(1):jrm00134. Epub 2021 Jan 1.

Physical Medicine and Rehabilitation, University of Texas Health Science Center McGovern Medical School and TIRR Memorial Hermann, Houston, TX 77030, USA. E-mail:

This consensus paper is derived from a meeting of an international group of 19 neurological rehabilitation specialists with a combined experience of more than 250 years (range 4-25 years; mean 14.1 years) in treating post-stroke spasticity with botulinum toxin A. The group undertook critical assessments of some recurring practical challenges, not yet addressed in guidelines, through an exten-sive literature search. They then discussed the results in the light of their individual clinical experience and developed consensus statements to present to the wider community who treat such patients. The analysis provides a comprehensive overview of treatment with botulinum toxin A, including the use of adjunctive therapies, within a multidisciplinary context, and is aimed at practicing clinicians who treat patients with post-stroke spasticity and require further practical guidance on the use of botulinum toxin A. This paper does not replicate information published elsewhere, but instead aims to provide practical advice to help optimize the use of botulinum toxin A and maximize clinical outcomes. The recommendations for each topic are summarized in a series of statements. Where published high-quality evidence exists, the recommendations reflect this. However, where evidence is not yet conclusive, the group members issued statements and, in some cas-es, made recommendations based on their clinical experience.
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http://dx.doi.org/10.2340/16501977-2753DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8772370PMC
January 2021

Chronic effects of muscle and nerve-directed stretching on tissue mechanics.

J Appl Physiol (1985) 2020 11 27;129(5):1011-1023. Epub 2020 Aug 27.

Laboratory of Movement, Interactions, Performance (EA 4334), Faculty of Sport Sciences, Nantes, University of Nantes, France.

Tissue-directed stretching interventions can preferentially load muscular or nonmuscular structures such as peripheral nerves. How these tissues adapt mechanically to long-term stretching is poorly understood. This randomized, single-blind, controlled study used ultrasonography and dynamometry to compare the effects of 12-wk nerve-directed and muscle-directed stretching programs versus control on maximal ankle dorsiflexion range of motion (ROM) and passive torque, shear wave velocity (SWV; an index of stiffness), and architecture of triceps surae and sciatic nerve. Sixty healthy adults were randomized to receive nerve-directed stretching, muscle-directed stretching, or no intervention (control). The muscle-directed protocol was designed to primarily stretch the plantar flexor muscle group, whereas the nerve-directed intervention targeted the sciatic nerve tract. Compared with the control group [mean; 95% confidence interval (CI)], muscle-directed intervention showed increased ROM (+7.3°; 95% CI: 4.1-10.5), decreased SWV of triceps surae (varied from -0.8 to -2.3 m/s across muscles), decreased passive torque (-6.8 N·m; 95% CI: -11.9 to -1.7), and greater gastrocnemius medialis fascicle length (+0.4 cm; 95% CI: 0.1-0.8). Muscle-directed intervention did not affect the SWV and size of sciatic nerve. Participants in the nerve-directed group showed a significant increase in ROM (+9.9°; 95% CI: 6.2-13.6) and a significant decrease in sciatic nerve SWV (> -1.8 m/s across nerve regions) compared with the control group. Nerve-directed intervention had no effect on the main outcomes at muscle and joint levels. These findings provide new insights into the long-term mechanical effects of stretching interventions and have relevance to clinical conditions where change in mechanical properties has occurred. This study demonstrates that the mechanical properties of plantar flexor muscles and sciatic nerve can adapt mechanically to long-term stretching programs. Although interventions targeting muscular or nonmuscular structures are both effective at increasing maximal range of motion, the changes in tissue mechanical properties (stiffness) are specific to the structure being preferentially stretched by each program. We provide the first in vivo evidence that stiffness of peripheral nerves adapts to long-term loading stimuli using appropriate nerve-directed stretching.
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http://dx.doi.org/10.1152/japplphysiol.00239.2019DOI Listing
November 2020

Room for improvement: metrological properties of passive muscle-tendon stiffness measures in children with cerebral palsy.

Eur J Appl Physiol 2020 Sep 26;120(9):1999-2000. Epub 2020 Jul 26.

Laboratoire Interuniversitaire de Biologie de La Motricité, Univ Lyon, UJM Saint-Etienne, Bâtiment IRMIS, 10 rue de la Marandière, 42270, Saint Priest en Jarez, France.

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http://dx.doi.org/10.1007/s00421-020-04434-1DOI Listing
September 2020

COVID-19 pandemic. What should Physical and Rehabilitation Medicine specialists do? A clinician's perspective.

Eur J Phys Rehabil Med 2020 Aug 19;56(4):515-524. Epub 2020 May 19.

Valduce Hospital, Villa Beretta Rehabilitation Center, Costamasnaga, Lecco, Italy.

COVID-19 pandemic is rapidly spreading all over the world, creating the risk for a healthcare collapse. While acute care and intensive care units are the main pillars of the early response to the disease, rehabilitative medicine should play an important part in allowing COVID-19 survivors to reduce disability and optimize the function of acute hospital setting. The aim of this study was to share the experience and the international perspective of different rehabilitation centers, treating COVID-19 survivors. A group of Physical Medicine and Rehabilitation specialists from eleven different countries in Europe and North America have shared their clinical experience in dealing with COVID-19 survivors and how they have managed the re-organization of rehabilitation services. In our experience the most important sequelae of severe and critical forms of COVID-19 are: 1) respiratory; 2) cognitive, central and peripheral nervous system; 3) deconditioning; 4) critical illness related myopathy and neuropathy; 5) dysphagia; 6) joint stiffness and pain; 7) psychiatric. We analyze all these consequences and propose some practical treatment options, based on current evidence and clinical experience, as well as several suggestions for management of rehabilitation services and patients with suspected or confirmed infection by SARS-CoV-2. COVID-19 survivors have some specific rehabilitation needs. Experience from other centers may help colleagues in organizing their services and providing better care to their patients.
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http://dx.doi.org/10.23736/S1973-9087.20.06317-0DOI Listing
August 2020

Effect of chronic stretching interventions on the mechanical properties of muscles in patients with stroke: A systematic review.

Ann Phys Rehabil Med 2020 May 22;63(3):222-229. Epub 2020 Jan 22.

School of Physiotherapy, IFM3R, 54, rue de la Baugerie, 44230 Saint-Sébastien-Sur-Loire, France; Movement - Interactions - Performance, MIP, EA 4334, university of Nantes, CHU Nantes, 44000 Nantes, France. Electronic address:

Background: Muscle contractures are common after stroke and their treatment usually involves stretching. However, recent meta-analyses concluded that stretching does not increase passive joint amplitudes in patients with stroke. The effectiveness of treatment is usually evaluated by measuring range of motion alone; however, assessing the effects of stretching on the structural and mechanical properties of muscle by evaluating the torque-angle relationship can help in understanding the effects of stretching. Although several studies have evaluated this, the effects remain unclear.

Objective: A systematic review of the literature on the effectiveness of stretching procedures for which the outcomes included a measurement of torque associated with range of motion or muscle structure (e.g., fascicle length) in stroke survivors.

Methods: PubMed, ScienceDirect and PEDro databases were searched by 2 independent reviewers for relevant studies on the effects of chronic stretching interventions (>4 weeks) that evaluated joint angle and passive torque or muscle structure or stiffness. The quality of the studies was assessed with the PEDro scale.

Results: Eight randomized clinical trials (total of 290 participants) met the inclusion criteria, with highly variable sample characteristics (at risk/existing contractures), program objectives (prevent/treat contractures) and duration (from 4 to 52 weeks) and volume of stretching (1 to 586 hr). All studies were classified as high quality (>6/10 PEDro score). Six studies focused on the upper limb. Many programs were less than 12 weeks (n=7 studies) and did not change mechanical/structural properties. The longest intervention (52 weeks) increased muscle fascicle length and thickness (plantar flexors).

Conclusion: Long interventions involving high stretching volumes and/or loads may have effects on muscle/joint mechanical properties, for preventing/treating contractures after stroke injury, but need to be further explored before firm conclusions are drawn.
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http://dx.doi.org/10.1016/j.rehab.2019.12.003DOI Listing
May 2020

What causes increased passive stiffness of plantarflexor muscle-tendon unit in children with spastic cerebral palsy?

Eur J Appl Physiol 2019 Oct 30;119(10):2151-2165. Epub 2019 Aug 30.

Univ Lyon, UJM Saint-Etienne, Laboratoire Interuniversitaire de biologie de la motricité, EA7424, 42023, Saint-Etienne, France.

Purpose: The term 'stiffness' is commonly used in the literature to refer to various components of 'hyperresistance' by which spastic muscles oppose to their passive lengthening, especially in children with cerebral palsy (CP). Originally, stiffness consists of mechanical resistance to passive movement in the absence of any muscle activation. Increased muscle stiffness in CP therefore refers to alterations to the mechanical properties of the tissue. It is closely linked to muscle shortening, yet the two phenomena are not equivalent. Both increased stiffness and shortening are present early in childhood in the plantarflexor muscles of children with spastic CP.

Methods: This narrative review provides a comprehensive overview of the literature on passive stiffness of the plantarflexor muscles measured at the joint, muscles, fascicles, and fiber level in children with CP. Articles were searched through the Pub'Med database using the keywords "cerebral palsy" AND "stiffness".

Result: The ambiguous use of the term 'stiffness' has been supported by discrepancies in available results, influenced by heterogeneity in materials, methodologies and characteristics of the participants among studies. Increased stiffness at the joint and muscle belly level may be explained by altered structural properties at the microscopic level.

Conclusion: This thorough investigation of the literature suggests that the pathophysiology and the time course of the development of stiffness and contracture remain to be elucidated. A consideration of both morphological and mechanical measurements in children with CP is important when describing the alterations in their plantarflexors.
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http://dx.doi.org/10.1007/s00421-019-04208-4DOI Listing
October 2019

Detection of pronator muscle overactivity in children with unilateral spastic cerebral palsy: Development of a semi-automatic method using EMG data.

Ann Phys Rehabil Med 2019 Nov 24;62(6):409-417. Epub 2019 Aug 24.

Motion analysis laboratory, physical medicine and rehabilitation, university hospital of Nantes, 44000 Nantes, France; Laboratory Movement-Interactions-Performance (MIP), EA 4334, university of Nantes, 44322 Nantes, France.

Background: The pronator teres and pronator quadratus muscles are frequently injected with neuromuscular blocking agents to improve supination in children with spastic cerebral palsy and limited active elbow supination. However, determining by simple clinical examination whether these muscles are overactive during active movement is difficult.

Objective: This study aimed to develop a semi-automatic method to detect pronator muscle overactivity by using surface electromyography (EMG) during active supination movements in children with cerebral palsy.

Methods: In total, 25 children with unilateral spastic cerebral palsy (10 males; mean [SD] age 10.6 [3.0] years) and 12 typically developing children (7 males; mean age 11.0 [3.0] years) performed pronation-supination movements at 0.50Hz. Kinematic parameters and surface EMG signals were recorded for both pronator muscles. Three experts visually assessed muscle overactivity in the EMG signals of the children with cerebral palsy, in comparison with the reference group. The reliability and discrimination ability of the visual assessments were analysed. Overactivity detection thresholds for the semi-automatic method were adjusted by using the visual assessment by the EMG experts. The positive and negative predictive values of the semi-automatic detection method were calculated.

Results: Intra-rater reliability of visual assessment by EMG experts was excellent and inter-rater reliability was moderate. For the 25 children with unilateral spastic cerebral palsy, EMG experts could discriminate different profiles of pronator overactivity during active supination: no pronator overactivity, one overactive pronator, or overactivity of both pronators. The positive and negative predictive values were 96% and 91%, respectively, for this semi-automatic detection method.

Conclusions: Detection of pronator overactivity by using surface EMG provides an important complement to the clinical examination. This method can be used clinically, with the condition that clinicians be aware of surface EMG limitations. We believe use of this method can increase the accuracy of treatment for muscle overactivity, resulting in improved motor function and no worsening of paresis.
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http://dx.doi.org/10.1016/j.rehab.2019.08.001DOI Listing
November 2019

Influence of low muscle activation levels on the ankle torque and muscle shear modulus during plantar flexor stretching.

J Biomech 2019 Aug 28;93:111-117. Epub 2019 Jun 28.

Nantes Université, Movement - Interactions - Performance, MIP, EA 4334, F-44000 Nantes, France; Health and Rehabilitation Research Institute, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand.

During stretching studies, surface electromyography (sEMG) is used to ensure the passive state of the muscle, for the characterization of passive muscle mechanical properties. Different thresholds (1%, 2% or 5% of maximal) are indifferently used to set "passive state". This study aimed to investigate the effects of a slight activity on the joint and muscle mechanical properties during stretching. The joint torque and muscle shear modulus of the triceps surae muscles were measured in fifteen healthy volunteers during ankle dorsiflexions: (i) in a "fully relaxed" state, (ii) during active conditions where participants were asked to produce an sEMG amplitude of 1%, 2% or 5% of their maximal sEMG amplitude of the triceps surae. The 1% condition was the only that did not result in significant differences in joint torque or shear modulus compared to the relaxed condition. In the 2% condition, increases in joint torque were found at 80% of the maximal angle in dorsiflexion, and in the shear modulus of gastrocnemius medialis and gastrocnemius lateralis at the maximal angle in dorsiflexion. During the 5% condition, joint torque and the shear modulus of gastrocnemius medialis were higher than during relaxed condition at angles larger than 40% of maximal angle in dorsiflexion. The results provide new insights on the thresholds that should be considered for the design of stretching studies. A threshold of 1% seems much more appropriate than a 2% or 5% threshold in healthy participants. Further studies are required to define similar thresholds for patients.
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http://dx.doi.org/10.1016/j.jbiomech.2019.06.018DOI Listing
August 2019

Recursive Decomposition of Electromyographic Signals With a Varying Number of Active Sources: Bayesian Modeling and Filtering.

IEEE Trans Biomed Eng 2020 02 6;67(2):428-440. Epub 2019 May 6.

Objective: This paper describes a sequential decomposition algorithm for single-channel intramuscular electromyography (iEMG) generated by a varying number of active motor neurons.

Methods: As in previous work, we establish a hidden Markov model of iEMG, in which each motor neuron spike train is modeled as a renewal process with inter-spike intervals following a discrete Weibull law and motor unit action potentials are modeled as impulse responses of linear time-invariant systems with known prior. We then expand this model by introducing an activation vector associated with the state vector of the hidden Markov model. This activation vector represents recruitment/derecruitment of motor units and is estimated together with the state vector using Bayesian filtering. Non-stationarity of the model parameters is addressed by means of a sliding window approach, thus making the algorithm adaptive to variations in contraction force and motor unit action potential waveforms.

Results: The algorithm was validated using simulated and experimental iEMG signals with varying number of active motor units. The experimental signals were acquired from the tibialis anterior and abductor digiti minimi muscles by fine wire and needle electrodes. The decomposition accuracy in both simulated and experimental signals exceeded 90%.

Conclusion: The recruitment/derecruitment was successfully tracked by the algorithm. Because of its parallel structure, this algorithm can be efficiently accelerated, which lays the basis for its real-time applications in human-machine interfaces.

Significance: The proposed method substantially broadens the domains of applicability of the algorithm.
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http://dx.doi.org/10.1109/TBME.2019.2914966DOI Listing
February 2020

3-D lower extremity bone morphology in ambulant children with cerebral palsy and its relation to gait.

Ann Phys Rehabil Med 2021 May 9;64(3):101254. Epub 2019 Apr 9.

Paediatric Physical and Rehabilitation Department, Ildys Fondation, Ty Yann Establishment, 29200 Brest, France; Physical and Rehabilitation Medicine Department, University Hospital of Brest, 29200 Brest, France; National Institute of Health and Medical Research (Inserm) UMR 1101, Medical Data Treatment (LaTIM), 29200 Brest, France; Western Britany University, 29200 Brest, France.

Changes in lower-extremity bone morphology are potential mid- to long-term secondary consequences of cerebral palsy (CP), affecting activity. Little is known about the 3-D morphology of lower-extremity bones in children with CP and the association with gait deviations. The main aim of this study was to describe and compare 3-D lower-extremity bone morphology in ambulant children with unilateral or bilateral CP. Secondary aims were to determine whether certain bone parameters were related to the unilateral or bilateral CP and to quantify the association between bone parameters and gait deviations. Among 105 ambulant children with CP (aged 3 to 17 years), 48 had bilateral CP (Bilat-CP) and 57 had unilateral CP (Unilat-CP); the unaffected limb of children with Unilat-CP was used as control limbs. Fifteen bone parameters were calculated by EOS® biplanar radiography, and the Gait Deviation Index (GDI) was calculated by 3-D gait analysis. Data were compared by descriptive and comparative statistical analysis (Anova, principal component analysis [PCA] and focused-PCA). Mean (SD) neck shaft angle was significantly greater for Unilat-CP than control limbs (134.9° [5.9] vs. 131.3° [5]). Mean mechanical tibial angle was significantly smaller (85.8° [6.7] vs. 89° [4.6]) and mean femoral torsion was significantly greater (29.4° [1.6] vs. 19.1° [11.8]) for Bilat-CP than control limbs. On PCA of the main determinants of 3-D bone morphology, bone shape was more complex with Bilat-CP, with changes in all 3 dimensions of space, than Unilat-CP and control limbs. Few bone parameters were correlated with the GDI in any limbs. In ambulant children with CP, femoral and tibial growth are not affected by the condition. The unilateral or bilateral nature of CP must be considered during treatment to prevent bone deformities and bone morphology affecting gait quality.
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http://dx.doi.org/10.1016/j.rehab.2019.03.001DOI Listing
May 2021

Reorganization of muscle synergies in 2 individuals with C5 and C6 tetraplegia after biceps-triceps and posterior deltoid-triceps tendon transfers.

Ann Phys Rehabil Med 2019 Mar 26;62(2):128-131. Epub 2018 Oct 26.

Motion analysis laboratory, Physical Medicine and Rehabilitation, University Hospital of Nantes, 44093 Nantes, France.

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http://dx.doi.org/10.1016/j.rehab.2018.09.008DOI Listing
March 2019

The potential role of sciatic nerve stiffness in the limitation of maximal ankle range of motion.

Sci Rep 2018 09 28;8(1):14532. Epub 2018 Sep 28.

Laboratory ≪Movement, Interactions, Performance≫ (EA 4334), Faculty of Sport Sciences, University of Nantes, Nantes, France.

It is a long held belief that maximal joint range of motion (ROM) is restricted by muscle tension. However, it exists indirect evidence suggesting that this assumption may not hold true for some joint configurations where non-muscular structures, such as the peripheral nerves, are stretched. Direct evidences are lacking. This study aimed to determine whether a static stretching aiming to load the sciatic nerve without stretch within plantar flexors is effective to: (i) alter nerve stiffness; and (ii) increase the ankle's maximal ROM. Passive maximal ankle ROM in dorsiflexion was assessed with the hip flexed at 90° (HIP-flexed) or neutral (HIP-neutral, 0°). Sciatic nerve stiffness was estimated using shear wave elastography. Sciatic nerve stretching induced both a 13.3 ± 7.9% (P < 0.001) decrease in the nerve stiffness and a 6.4 ± 2.6° increase in the maximal dorsiflexion ROM assessed in HIP-flexed. In addition, the decrease in sciatic nerve stiffness was significantly correlated with the change in maximal ROM in dorsiflexion (r = -0.571, P = 0.026). These effects occurred in the absence of any change in gastrocnemius medialis and biceps femoris stiffness, and ankle passive torque. These results demonstrate that maximal dorsiflexion ROM can be acutely increased by stretching the sciatic nerve, without altering the muscle stiffness.
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http://dx.doi.org/10.1038/s41598-018-32873-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6162234PMC
September 2018

Effects of stroke injury on the shear modulus of the lower leg muscle during passive dorsiflexion.

J Appl Physiol (1985) 2019 01 20;126(1):11-22. Epub 2018 Sep 20.

University of Nantes, Laboratory "Movement, Interactions, Performance" (EA 4334), Faculty of Sport Sciences , Nantes , France.

Contractures are common complications of a stroke. The spatial location of the increased stiffness among plantar flexors and its variability among survivors remain unknown. This study assessed the mechanical properties of the lower leg muscles in stroke survivors during passive dorsiflexions. Stiffness was estimated through the measurement of the shear modulus. Two experiments were independently conducted, in which participants lay supine: with the knee extended ( experiment 1, n = 13 stroke survivors and n = 13 controls), or with the knee flexed at 90° ( experiment 2, n = 14 stroke survivors and n = 14 controls). The shear modulus of plantar flexors [gastrocnemius medialis (three locations), gastrocnemius lateralis (three locations), soleus (two locations), flexor digitorum longus, flexor hallucis longus), peroneus longus] and dorsiflexors (tibialis anterior and extensor digitorum longus) was measured using ultrasound shear wave elastography during passive dorsiflexions (2°/s). At the same ankle angle, stroke survivors displayed higher shear modulus than controls for gastrocnemius medialis and gastrocnemius lateralis (knee extended) and soleus (knee flexed). Very low shear modulus was found for the other muscles. The adjustment for muscle slack angle suggested that the increased shear modulus was arising from consequences of contractures. The stiffness distribution between muscles was consistent across participants with the highest shear modulus reported for the most distal regions of gastrocnemius medialis (knee extended) and soleus (knee flexed). These results provide a better appreciation of stiffness locations among plantar flexors of stroke survivors and can provide evidence for the implementation of clinical trials to evaluate targeted interventions applied on these specific muscle regions. NEW & NOTEWORTHY The shear modulus of 13 muscle regions was assessed in stroke patients using elastography. When compared with controls, shear modulus was increased in the gastrocnemius muscle (GM) when the knee was extended and in the soleus (SOL) when the knee was flexed. The distal regions of GM and SOL were the most affected. These changes were consistent in all the stroke patients, suggesting that the regions are a potential source of the increase in joint stiffness.
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http://dx.doi.org/10.1152/japplphysiol.00968.2017DOI Listing
January 2019

Patterns of upper limb muscle activation in children with unilateral spastic cerebral palsy: Variability and detection of deviations.

Clin Biomech (Bristol, Avon) 2018 11 5;59:85-93. Epub 2018 Sep 5.

Motion Analysis Laboratory, Physical Medicine and Rehabilitation, University Hospital of Nantes, Nantes, France; Laboratory of Movement - Interactions - Performance (MIP), EA 4334, University of Nantes, Nantes, France. Electronic address:

Background: The aim of this study was two-fold: (1) to quantify the variability of upper limb electromyographic patterns during elbow movements in typically developing children and children with unilateral spastic cerebral palsy, and to compare different amplitude normalization methods; (2) to develop a method using this variability to detect (a) deviations in the patterns of a child with unilateral spastic cerebral palsy from the average patterns of typically developing children, and (b) changes after treatment to reduce muscle activation.

Methods: Twelve typically developing children ([6.7-15.9yo]; mean 11.0 SD 3.0yo) and six children with unilateral spastic cerebral palsy ([7.9-17.4yo]; mean 12.4 SD 4.0yo) attended two sessions during which they performed elbow extension-flexion and pronation-supination movements. Surface electromyography of the biceps, triceps, brachioradialis, pronator teres, pronator quadratus, and brachialis muscles was recorded. The Likelihood method was used to estimate the inter-trial, inter-session, and inter-subject variability of the electromyography patterns for each time point in the movement cycle. Deviations in muscle patterns from the patterns of typically developing children and changes following treatment were evaluated in a case study of a child with cerebral palsy.

Findings: Normalization of electromyographic amplitude by the mean peak yielded the lowest variability. The variability data were then used in the case study. This method detected higher levels of activation in specific muscles compared with typically developing children, and a reduction in muscle activation after botulinum toxin A injections.

Interpretation: Upper limb surface electromyography pattern analysis can be used for clinical applications in children with cerebral palsy.
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http://dx.doi.org/10.1016/j.clinbiomech.2018.09.005DOI Listing
November 2018

Passive stiffness of monoarticular lower leg muscles is influenced by knee joint angle.

Eur J Appl Physiol 2018 Mar 11;118(3):585-593. Epub 2018 Jan 11.

Laboratory "Movement, Interactions, Performance" (EA 4334), Faculty of Sport Sciences, Université de Nantes, UFR STAPS, 25 bis Bd Guy Mollet, BP 72206, 44000, Nantes, France.

Purpose: While several studies demonstrated the occurrence of intermuscular mechanical interactions, the physiological significance of these interactions remains a matter of debate. The purpose of this study was to quantify the localized changes in the shear modulus of the gastrocnemius lateralis (GL), monoarticular dorsi- and plantar-flexor muscles induced by a change in knee angle.

Method: Participants underwent slow passive ankle rotations at the following two knee positions: knee flexed at 90° and knee fully extended. Ultrasound shear wave elastography was used to assess the muscle shear modulus of the GL, soleus [both proximally (SOL-proximal) and distally (SOL distal)], peroneus longus (PERL), and tibialis anterior (TA). This was performed during two experimental sessions (experiment I: n = 11; experiment II: n = 10). The shear modulus of each muscle was compared between the two knee positions.

Results: The shear modulus was significantly higher when the knee was fully extended than when the knee was flexed (P < 0.001) for the GL (averaged increase on the whole range of motion: + 5.8 ± 1.3 kPa), SOL distal (+ 4.5 ± 1.5 kPa), PERL (+ 1.1 ± 0.7 kPa), and TA (+ 1.6 ± 1.0 kPa). In contrast, a lower SOL-proximal shear modulus (P < 0.001, - 5.9 ± 1.0 kPa) was observed.

Conclusion: As the muscle shear modulus is linearly related to passive muscle force, these results provide evidence of a non-negligible intermuscular mechanical interaction between the human lower leg muscles during passive ankle rotations. The role of these interactions in the production of coordinated movements requires further investigation.
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http://dx.doi.org/10.1007/s00421-018-3798-yDOI Listing
March 2018

Surgical management of lower limb fractures in patients with spinal cord injury less associated with complications than non-operative management: A retrospective series of cases.

J Spinal Cord Med 2019 01 10;42(1):39-44. Epub 2017 May 10.

a Physical Medicine and Rehabilitation Department , University Hospital of Nantes , France.

Objectives: To evaluate the difference in terms of overall complications between surgical and non-surgical management of lower limb fractures in patients with chronic spinal cord injury (SCI).

Design: A 13-year retrospective study including patients with chronic spinal cord lesion admitted for sublesional lower limb fractures.

Setting: University hospital SCI reference departments (Rehabilitation department and orthopedic department).

Participants: Forty patients with SCI were included, 24 men and 16 women. Fifty-six distinct fracture occurrences were responsible for a total of 59 lower limb fractures. We compared the number of overall complications between surgical and non-surgical management of fractures.

Results: Non-surgical management was realized for 19 fractures and surgery for 40. Characteristics of operated and non-operated patients at the time of each fracture occurrence did not differ concerning age (P = 0.430), sex (P = 0.890), lesion levels (P = 0.410) and AIS classification (P = 0.790). Data analysis highlighted 20 complications directly due to the fracture site for 16 distinct fractures. Seven medical complications were found in 5 distinct fracture events. Only 10 (25.0%) of 40 surgical managements had at least one medical or post-surgical complication, whereas 12 (63.2%) of 19 non-operative managements had at least one complication. Therefore, the overall rate of complications was significantly higher after non-surgical treatment (P = 0.044).

Conclusion: Lower extremity fractures due to osteoporosis in patients with SCI are responsible for local and general complications. When possible, surgery may be the best management to propose because of fewer overall complications.
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http://dx.doi.org/10.1080/10790268.2017.1325560DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6340277PMC
January 2019

Non-Muscular Structures Can Limit the Maximal Joint Range of Motion during Stretching.

Sports Med 2017 Oct;47(10):1925-1929

Laboratory "Movement, Interactions, Performance" (EA 4334), Faculty of Sport Sciences, University of Nantes, 25 Bis Boulevard Guy Mollet, BP 72206, 44322, Nantes Cedex 3, France.

Stretching is widely used in sport training and clinical practice with the aim of increasing muscle-tendon extensibility and joint range of motion. The underlying assumption is that extensibility increases as a result of increased passive tension applied to muscle-tendon units. In some stretching protocols, this condition is not always met sufficiently to trigger adaptation within the muscle-tendon unit. For example, there is experimental evidence that both acute and chronic stretching interventions may increase the maximal range of motion in the absence of changes in the passive torque-angle curve. We contend that these results are partly explained by the influence of non-muscular structures that contribute only marginally to the passive torque. The potential candidates are the nervous system and fasciae, which would play an important role in the perception of the stretch and in the limitation of the range of motion of the maximal joints. At least in part, this may explain the lack of a significant effect of some chronic stretching interventions to change passive muscle tension.
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http://dx.doi.org/10.1007/s40279-017-0703-5DOI Listing
October 2017

Stiffness mapping of lower leg muscles during passive dorsiflexion.

J Anat 2017 May 2;230(5):639-650. Epub 2017 Mar 2.

University of Nantes, Laboratory 'Movement, Interactions, Performance' (EA 4334), Faculty of Sport Sciences, Nantes, France.

It is challenging to differentiate the mechanical properties of synergist muscles in vivo. Shear wave elastography can be used to quantify the shear modulus (i.e. an index of stiffness) of a specific muscle. This study assessed the passive behavior of lower leg muscles during passive dorsiflexion performed with the knee fully extended (experiment 1, n = 22) or with the knee flexed at 90° (experiment 2, n = 20). The shear modulus measurements were repeated twice during experiment 1 to assess the inter-day reliability. During both experiments, the shear modulus of the following plantar flexors was randomly measured: gastrocnemii medialis (GM) and lateralis (GL), soleus (SOL), peroneus longus (PL), and the deep muscles flexor digitorum longus (FDL), flexor hallucis longus (FHL), tibialis posterior (TP). Two antagonist muscles tibialis anterior (TA), and extensor digitorum longus (EDL) were also recorded. Measurements were performed in different proximo-distal regions for GM, GL and SOL. Inter-day reliability was adequate for all muscles (coefficient of variation < 15%), except for TP. In experiment 1, GM exhibited the highest shear modulus at 80% of the maximal range of motion (128.5 ± 27.3 kPa) and was followed by GL (67.1 ± 24.1 kPa). In experiment 2, SOL exhibited the highest shear modulus (55.1 ± 18.0 kPa). The highest values of shear modulus were found for the distal locations of both the GM (80% of participants in experiment 1) and the SOL (100% of participants in experiment 2). For both experiments, deep muscles and PL exhibited low levels of stiffness during the stretch in young asymptomatic adults, which was unknown until now. These results provide a deeper understanding of passive mechanical properties and the distribution of stiffness between and within the plantar flexor muscles during stretching between them and thus could be relevant to study the effects of aging, disease progression, and rehabilitation on stiffness.
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http://dx.doi.org/10.1111/joa.12589DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5382595PMC
May 2017

Effects of Duchenne muscular dystrophy on muscle stiffness and response to electrically-induced muscle contraction: A 12-month follow-up.

Neuromuscul Disord 2017 Mar 6;27(3):214-220. Epub 2017 Jan 6.

Laboratory (Movement, Interactions, Performance) (EA 4334), Faculty of Sport Sciences, University of Nantes, France.

The present study aimed to assess the ability of muscle stiffness (shear modulus) and response to electrically-induced muscle contraction to detect changes in muscle properties over a 12-month period in children with Duchenne muscular dystrophy (DMD). Ten children with DMD and nine age-matched healthy male controls participated in two experimental sessions (T and T) separated by 12.4 ± 0.9 months. Two contractions of the biceps brachii were electrically-induced during which an ultrasound probe was placed over the muscle. The resting shear modulus was measured using elastography from six muscles. Evoked maximal torque was increased at T in controls (+11.2 ± 7.6%, P <0.001) but was not modified in children with DMD (P = 0.222). Electromechanical delay (+12.9 ± 11.3%, P <0.001) and its force transmission component (+10.1 ± 21.6%, P = 0.003) were significantly longer at T than T for children with DMD. The results revealed an increase in muscle stiffness at T in children with DMD for tibialis anterior (+75.1 ± 93.5%, P= 0.043), gastrocnemius medialis (+144.8 ± 180.6%, P= 0.050) and triceps brachii (+35.5 ± 32.2%, P= 0.005). This 12-month follow-up study demonstrates that electromechanical delay and elastography may help detect subtle muscle impairments in patients with DMD. These sensitive outcomes may improve the follow-up of innovative therapeutic interventions within the field of DMD.
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http://dx.doi.org/10.1016/j.nmd.2017.01.001DOI Listing
March 2017

Muscle Activation during Gait in Children with Duchenne Muscular Dystrophy.

PLoS One 2016 13;11(9):e0161938. Epub 2016 Sep 13.

Laboratoire de Traitement de l'Information Médicale INSERM U1101, Brest, France.

The aim of this prospective study was to investigate changes in muscle activity during gait in children with Duchenne muscular Dystrophy (DMD). Dynamic surface electromyography recordings (EMGs) of 16 children with DMD and pathological gait were compared with those of 15 control children. The activity of the rectus femoris (RF), vastus lateralis (VL), medial hamstrings (HS), tibialis anterior (TA) and gastrocnemius soleus (GAS) muscles was recorded and analysed quantitatively and qualitatively. The overall muscle activity in the children with DMD was significantly different from that of the control group. Percentage activation amplitudes of RF, HS and TA were greater throughout the gait cycle in the children with DMD and the timing of GAS activity differed from the control children. Significantly greater muscle coactivation was found in the children with DMD. There were no significant differences between sides. Since the motor command is normal in DMD, the hyper-activity and co-contractions likely compensate for gait instability and muscle weakness, however may have negative consequences on the muscles and may increase the energy cost of gait. Simple rehabilitative strategies such as targeted physical therapies may improve stability and thus the pattern of muscle activity.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0161938PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5021331PMC
August 2017

Neuromuscular Changes and Damage after Isoload versus Isokinetic Eccentric Exercise.

Med Sci Sports Exerc 2016 12;48(12):2526-2535

1Laboratory "Movement, Interactions, Performance" (EA 4334), Faculty of Sport Sciences, University of Nantes, Nantes, FRANCE; 2Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, AUSTRALIA; 3Department of Physical Medicine and Rehabilitation, Nantes University Hospital, Saint-Jacques Hospital, Nantes, FRANCE; and 4French Institute of Sport (INSEP), Research Department, Laboratory Sport, Expertise and Performance (EA 7370), Paris, FRANCE.

Purpose: This study compared the effects of isoload (IL) and isokinetic (IK) knee extensor eccentric exercises on changes in muscle damage and neuromuscular parameters to test the hypothesis that the changes would be different after IL and IK exercises.

Methods: Twenty-two young men were paired based on their strength and placed in the IL (N = 11) or the IK (N = 11) group. The IL group performed 15 sets of 10 eccentric contractions with a 150% of predetermined one-repetition maximum load. The IK group performed 15 sets of several maximal eccentric contractions matched set by set for the total amount of work and mean angular velocity with the IL group. Muscle damage markers (voluntary isometric peak torque, muscle soreness, and creatine kinase activity) and neuromuscular variables (e.g., voluntary activation, H-reflex, M-wave, and evoked torque) were measured before, immediately after, and 24, 48, 72, and 96 h postexercise.

Results: Voluntary isometric peak torque decreased to the same extent (P = 0.94) in both groups immediately after (IL = -40.6% ± 13.8% vs IK = -42.4% ± 10.2%) to 96 h after the exercise (IL = -21.8% ± 28.5% vs IK = -26.7% ± 23.5%). Neither peak muscle soreness (IL = 48.1 ± 28.2 mm vs IK = 54.7 ± 28.9 mm, P = 0.57) nor creatine kinase activity (IL = 12,811 ± 22,654 U·L vs IK = 15,304 ± 24,739 U·L, P = 0.59) significantly differed between groups. H-reflex (IL = -23% vs IK = -35%) and M-wave (IL = -10% vs IK = -17%) significantly decreased immediately postexercise similarly between groups.

Conclusion: The changes in muscle damage and neuromuscular function after the exercise are similar between IL and IK, suggesting that resistance modality has little effects on acute muscle responses.
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http://dx.doi.org/10.1249/MSS.0000000000001042DOI Listing
December 2016

Comparison of total ankle replacement and ankle arthrodesis in patients with haemophilia using gait analysis: two case reports.

BMC Res Notes 2015 Dec 10;8:768. Epub 2015 Dec 10.

CHU Nantes, Centre Régional de Traitement de l'Hémophilie, Hôtel Dieu, 44035, Nantes Cedex 03, France.

Background: Severe hemophilia is an inherited, lifelong bleeding disorder characterized by spontaneous bleeding, which results in painful joint deformities. Currently two surgical treatments are available to treat haemophilia-related ankle joint destruction: ankle arthrodesis and total ankle replacement. The aim of the present study was to compare these two surgical procedures in haemophiliac subjects.

Case Presentation: Kinematic and dynamic parameters were quantified using a three-dimensional gait-analysis system in two similar clinical cases. In Caucasian case 1, ankle arthrodesis was chosen because of a kinematic ankle flexion defect and lack of dynamic power regeneration. The defect in energy absorption was compensated for by the contralateral side. Total ankle replacement in Caucasian case 2 allowed sparing the ipsilateral knee (maximum 0.27 preoperatively vs. 0.71 W/kg postoperatively) and hip joints powers (maximum 0.43 preoperatively vs. 1.25 W/kg postoperatively) because of the small ankle dorsiflexion motion.

Conclusions: Total ankle replacement is recommended for haemophiliac patients who present with a preserved ankle range of motion.
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http://dx.doi.org/10.1186/s13104-015-1763-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4676108PMC
December 2015

Does muscle coactivation influence joint excursions during gait in children with and without hemiplegic cerebral palsy? Relationship between muscle coactivation and joint kinematics.

Clin Biomech (Bristol, Avon) 2015 Dec 8;30(10):1088-93. Epub 2015 Sep 8.

Laboratoire de Traitement de l'Information Médicale INSERM U650, Brest, France; Université de Bretagne Occidentale, Brest, France; CHRU Brest, Hôpital Morvan, service médecine physique et réadaptation, Brest, France.

Background: The theoretical role of muscle coactivation is to stiffen joints. The aim of this study was to assess the relationship between muscle coactivation and joint excursions during gait in children with and without hemiplegic cerebral palsy.

Methods: Twelve children with hemiplegic cerebral palsy and twelve typically developing children underwent gait analysis at three different gait speeds. Sagittal hip, knee, and ankle kinematics were divided into their main components corresponding to joint excursions. A coactivation index was calculated for each excursion from the electromyographic envelopes of the rectus femoris/semitendinosus, vastus medialis/semitendinosus, or tibialis anterior/soleus muscles. Mixed linear analyses of covariance modeled joint excursions as a function of the coactivation index and limb.

Findings: In typically developing children, increased coactivation was associated with reduced joint excursion for 8 of the 14 linear models (hip flexion, knee loading, knee extension in stance, knee flexion in swing, ankle plantarflexion from initial contact to foot-flat, ankle dorsiflexion in stance and in swing). Conversely, ankle plantarflexion excursion at push-off increased with increasing tibialis anterior/soleus coactivation. In the involved limbs of the children with cerebral palsy, knee loading, ankle plantarflexion at push off, and ankle dorsiflexion in swing decreased, while hip extension increased, with increasing muscle coactivation.

Interpretation: The relationships between muscle coactivation and joint excursion were not equally distributed in both groups, and predominant in typically developing children. The results suggest that excessive muscle coactivation is not a cause of stiff-knee gait in children with hemiplegic cerebral palsy, but appears to be related to spastic drop foot.
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http://dx.doi.org/10.1016/j.clinbiomech.2015.09.001DOI Listing
December 2015

Changes in muscle activity in typically developing children walking with unilaterally induced equinus.

Clin Biomech (Bristol, Avon) 2014 Dec 5;29(10):1116-24. Epub 2014 Oct 5.

CHRU de Brest, Hôpital Morvan, Service de Médecine Physique et Réadaptation, Brest, France; Laboratoire de Traitement de l'Information Médicale INSERM U1101, Brest, France; Université de Bretagne Occidentale, Brest, France.

Background: Distinguishing changes in lower limb muscle activation during gait caused by abnormal motor control or adaptations to the presence of a fixed equinus remains a challenge. The objective of this study was to determine a threshold degree of equinus at which changes in muscle activity occur and to characterize adaptive patterns of muscle activity in typically developing children walking with unilateral induced equinus.

Methods: Ten typically developing children were included. A customized orthosis was fitted to the right ankle. Five conditions of dorsiflexion limitation were evaluated: 10° dorsiflexion, 0°, 10°, 20° of plantar flexion and maximum plantar flexion. Muscle activity of the rectus femoris, vastus lateralis, hamstring, tibialis anterior and soleus muscles of both limbs was recorded.

Findings: Significant changes in muscle activation and co-activation occurred from 10° of plantar flexion in the orthosis limb and from maximum plantar flexion in the contralateral limb. Soleus activation occurred prematurely in terminal swing and increased with the degree of equinus. Tibialis anterior activation was increased during initial and midswing and was decreased during terminal swing. From the -20° condition, hamstring activation was increased during the loading response. Vastus lateralis and rectus femoris activation was increased during stance phase. Similar changes in tibialis anterior and soleus activation occurred on the contralateral side. Changes in co-activation occurred in the soleus/tibialis anterior muscle pair in both limbs.

Interpretation: This study provides indications regarding changes in muscle activity during simulation of equinus gait which should be helpful for therapeutic decision making.
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http://dx.doi.org/10.1016/j.clinbiomech.2014.09.015DOI Listing
December 2014

Benefits of repetitive transcranial magnetic stimulation (rTMS) for spastic subjects: clinical, functional, and biomechanical parameters for lower limb and walking in five hemiparetic patients.

ScientificWorldJournal 2014 29;2014:389350. Epub 2014 Apr 29.

Department of Neurosurgery and Neurotraumatology, CHU de Nantes, 1, place Alexis Ricordeau, 44093 Nantes, France ; UMR CNRS 7338 Biomécanique et Bioingénierie, Université de Technologies de Compiègne, BP 20529, 60205 Compiègne, France ; INSERM EA3826, "Pain, Neuromodulation, and Quality of Life", CHU de Nantes, 1, place Alexis Ricordeau, 44093 Nantes, France.

Introduction. Spasticity is a disabling symptom resulting from reorganization of spinal reflexes no longer inhibited by supraspinal control. Several studies have demonstrated interest in repetitive transcranial magnetic stimulation in spastic patients. We conducted a prospective, randomized, double-blind crossover study on five spastic hemiparetic patients to determine whether this type of stimulation of the premotor cortex can provide a clinical benefit. Material and Methods. Two stimulation frequencies (1 Hz and 10 Hz) were tested versus placebo. Patients were assessed clinically, by quantitative analysis of walking and measurement of neuromechanical parameters (H and T reflexes, musculoarticular stiffness of the ankle). Results. No change was observed after placebo and 10 Hz protocols. Clinical parameters were not significantly modified after 1 Hz stimulation, apart from a tendency towards improved recruitment of antagonist muscles on the Fügl-Meyer scale. Only cadence and recurvatum were significantly modified on quantitative analysis of walking. Neuromechanical parameters were modified with significant decreases in H max⁡ /M max⁡ and T/M max⁡ ratios and stiffness indices 9 days or 31 days after initiation of TMS. Conclusion. This preliminary study supports the efficacy of low-frequency TMS to reduce reflex excitability and stiffness of ankle plantar flexors, while clinical signs of spasticity were not significantly modified.
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http://dx.doi.org/10.1155/2014/389350DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4032683PMC
February 2015

The influence of gait speed on co-activation in unilateral spastic cerebral palsy children.

Clin Biomech (Bristol, Avon) 2013 Mar 8;28(3):312-7. Epub 2013 Feb 8.

Laboratoire d'analyse du Mouvement, Pôle Médecine Physique et Réadaptation, hôpital Saint Jacques, CHU Nantes, Nantes, France.

Background: Physiological co-activation of antagonistic muscles during gait allows stability of loaded joints. Excessive co-activation restrains motion and increases energy expenditure. Co-activation is increased by gait speed and in the case of upper motor neuron lesions. This study aimed to assess the pathological component of co-activation in children with unilateral cerebral palsy.

Methods: 10 children with unilateral cerebral palsy and 10 typically developing children walked at spontaneous, slow and fast speeds. The spatio-temporal parameters and electromyographic activity of the rectus femoris, vastus medialis, semi-tendinosus, tibialis anterior and soleus of both lower limbs were recorded. A co-activation index was computed from the EMG envelopes. A mixed linear model was used to assess the effect of walking speed on the index of the antagonistic muscle couples (rectus femoris/semi-tendinosus, vastus medialis/semi-tendinosus and tibialis anterior/soleus) in the different limbs.

Findings: A greater effect of walking speed on co-activation was found in the involved limbs of children with cerebral palsy for all muscle couples, compared with their uninvolved limbs and the limbs of typically developing children. In typically developing children, but not in children with cerebral palsy, the effect of gait speed on the co-activation index was lower in the rectus femoris/semi-tendinosus than in the other agonist/antagonist muscle couples.

Interpretations: In children with cerebral palsy, a pathological component of muscle activation might be responsible for the greater increase in co-activation with gait speed in the involved limb. Altered motor control could explain why the co-activation in the rectus femoris/semi-tendinosus couple becomes more sensitive to speed.
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http://dx.doi.org/10.1016/j.clinbiomech.2013.01.002DOI Listing
March 2013

Focal myositis of the calf following S1 radiculopathy.

Semin Arthritis Rheum 2008 Aug 21;38(1):20-7. Epub 2008 Feb 21.

Department of Rheumatology, Le Mans General Hospital, Le Mans, France.

Objectives: To determine the clinical, pathological, and magnetic resonance imaging (MRI) characteristics and outcome of focal myositis of the calf associated with S1 radiculopathy.

Methods: Case report and systematic review of literature using a literature review based on a Medline search from 1950 to 2006. Only cases with myositis documented on muscle biopsy examination were included.

Results: Six patients, including ours, with focal myositis of the calf associated with chronic S1 radiculopathy have been reported. Creatine phosphokinase levels were high in 5 cases. MRI provided evidence of global hypertrophy and inflammatory signals affecting the whole of 1 or several muscle heads of the triceps. Electromyography confirmed the existence of neurogenic abnormalities with nearly constant spontaneous activity. Histological analysis of muscle tissue showed an inflammatory infiltrate and denervation lesions. Progression was slow and corticosteroid treatment had little effect. There was no extension toward a diffuse form.

Conclusions: Hypertrophy in a denervated muscle should lead the physician to consider a diagnosis of localized secondary myositis. On the other hand, localized hypertrophic myositis is suggestive of previous radicular distress in the territory concerned. The identification of this condition in focal myositis makes it possible to avoid unnecessary additional investigations and escalation of treatment.
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http://dx.doi.org/10.1016/j.semarthrit.2007.09.004DOI Listing
August 2008
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